This invention relates to tissue processing apparatus for the processing of histological and like tissue specimens by sequential treatment with a series of reagents. More particularly the invention relates to tissue processing apparatus of the kind comprising a single processing chamber for the reception of one or more tissue specimens and to which reagents are supplied, in turn, for the sequential treatment of the tissue specimen(s) therein with such reagents. Typically in the preparation of tissue specimens for microscopic examination, the specimens are subjected progressively to fixation, dehydration, clearing, staining and embedding in a suitable wax to facilitate sectioning of the tissue specimens. The dehydration stage usually involves the treatment of a batch of specimens with alcohol reagents of progressively increasing concentration, and the clearing stage involves the treatment of these dehydrated specimens one or more times with a clearing agent such as xylene to displace the alcohol. The dehydration and clearing stages as well as preceding fixations and/or subsequent staining and/or wax embedding stage may all be accomplished in the single processing chamber of apparatus of the kind with which the invention is concerned, by feeding the relevant processing fluids to that chamber, in turn, from individual sources.
Known single-chamber apparatus of this kind, for instance apparatus such as disclosed in U.S. Pat. Nos. 2,959,151, 3,227,130 and 4,141,312, utilises a variety of arrangements for feeding the various fluids to the processing chamber and for removing those fluids from the chamber following a treatment phase with such a fluid. However none of these arrangements makes significant provision fully to prevent the escape into the environment of leakages of the processing fluids and of their vapours, for instance in the air displaced from the processing chamber on admission of fluid thereto and in the air displaced from containers for the processing fluids during transfer of such fluids to and from the processing chamber. As many of the processing fluids are volatile their vapours are contained in significant amounts in the air displaced from the processing chamber and the fluid containers.
Moreover, the fluids become contaminated with materials eluted from the tissue specimens treated by the fluids and such materials (which may be highly toxic) may appear in the said displaced air and escape capture by any means that may be provided, such as activated carbon filters in air vent lines, for limiting the discharge of the processing fluid vapours.
The aim of the present invention is to avoid or mitigate this problem.